‘240 Bulletin American Museum of Natural History [Vol. LIII 
Distinguished from Anceya by the minute size, the less sinuous outer 
lip and the appearance of the basal cord at an early neanic stage. This 
cord remains small in the adult stage, not becoming a keel there as in 
Anceya. 
Martelia tanganyicensis Dautzenberg 
Martelia tanganyicensis DautTZENBERG, 1908 (March 30), Journ. de Conchyl., 
LV, (1907), p. 329, Pl. rv, figs. 11 and 12. 
Lake Tanganyika: described from Mpala, on the western coast (Guillemé 
Coll.). Albertville (Charles Hedley Coll.). . 
The specimens taken by Charles Hedley (Fig. 38) 
have the axial ribs prominent at the shoulder, more or 
less pointed, about eight on the face of the last whorl. 
‘The color is transparent brown or white, with a brown 
band below the suture, another just above the weak 
basal cord. The first two whorls are smooth and 
rounded, very fine axial riblets then appearing. The 
last three and a half whorls have coarse ribs. 
Length, 2.3 mm : diameter, 1.2 mm.; 6 whorls. 
Martelia dautzenbergi Dupuis 
Fig. 38. Mar- 
telia tanganyi- Martelia dautzenbergi Dupuis, 1924 (May) , Ann. Soc. Zool. 
censis Dautzen- Belgique, LIV, (1923), p. 20, fig. 1 (on p. 26). 
berg. | Lake Tanganyika: described from the western coast, 
without more definite locality. 
Truncatellide 
Shell imperforate, cylindric, of few whorls by loss of the tapering earlier portion, 
or if entire, elongate and many-whorled. Aperture oval; peristome blunt. Oper- 
culum thin, corneous, subspiral. 
Animal with a very large, long rostrum and tapering tentacles with eyes sessile 
at their posterior bases. Foot short. Pallial cavity very large, containing a small oll 
of many triangular ciliated lamellae. Radula (Fig. 39) with 3-1-3 teeth, the central 
triangular, unicuspid, with a mesially interrupted row of basal denticles ; laterals 
transverse, with few large denticles; marginals having a long body and numerous 
denticles. 
Locomotion is by looping, the oral disc and the foot being advanced 
alternately. Placed in water they are said to glide in the ordinary 
fashion of gastropods. 
They are small snails, mainly of the tropics of both hemispheres. 
The typical genus, Truncatella, lives under trash at extreme high tide 
line, or under stones, wood, etc., somewhat higher, always in the neigh- 
borhood of the sea. This genus is remarkable for its peculiar looping 
gait and the unicuspid central tooth of the radula. 
